We hired a private tour guide in Messina. We used Sicily Life and Sebastiano was our guide. This tour was organized by one of our cruisemates on our Oct. 2005 Med. cruise. We had 15 people sign up and thought that we would be having 2 vans for our tour. However, when we got off the ship we had a large bus waiting for us. We had lots of room to spread out on the bus. There was a driver for the bus also. Sebastiano did the commentary and spoke excellent English. He was very accommodating as far as what we wanted to see and do. We stopped in the square in Messina to see the Cathedral with the revolving figures on it. Also visited the area where they filmed the Godfather, then to Taormina. Very nice day.
I think you would be better off hiring a private guide that would be able to fit you all in the same vehicle. That way you will all get the same tour and won't get separated on those winding roads. We had 2 vans in several ports and I felt the bus worked out better for us.
Hope this helps.